When building nests, birds collect various types of natural materials such as grass reeds, straw and the like, and they also collect certain man-made materials such as string, and bits of cloth. Relatively long pieces of string have been known to endanger the lives of birds when they become tangled in it, and therefor, attempted use by birds of such materials should be discouraged. One way to do this is to make a supply of safe nest-building materials available to the birds during nest building time.